Inertial sensors as such are known and make it possible, in particular, to measure translational and/or rotational changes in movement. Inertial sensors that measure translational acceleration forces may also be referred to as acceleration sensors. Inertial sensors that measure rotational acceleration forces may also be referred to as rotational acceleration sensors. Inertial sensors that measure angular velocities during rotational movements may also be referred to as yaw rate sensors.
Known inertial sensors, in particular micromechanical inertial sensors, i.e., inertial sensors that have dimensions in the micrometer range, usually include a spring-mass system. In surface micromechanics, for example, the mass, which may also be referred to as a seismic mass, and the springs are etched from a functional layer, for example a silicon functional layer, which has layer thicknesses, in particular, between 10 μm and 20 μm. Since the usual structure widths in micromechanics range between 1 μm and 5 μm, the springs are much higher, than they are wide, i.e., an aspect ratio (the ratio between height and width) is much greater than 1. Springs of this type have a high rigidity in the Z direction, i.e., parallel to height. However, such springs are also very flexurally resilient in the X direction and are therefore frequently used as bending springs in the lateral direction, i.e., in the X direction.
Alternatively, a spring of an inertial sensor may also be formed in an additional functional layer in the sensor core. Since this additional functional layer in the sensor core is much thinner than the aforementioned functional layer, the spring provided in the sensor core has an aspect ratio of much less than 1. Springs of this type, however, are obviously not only torsionally resilient but also flexurally resilient in the Z direction, while they are very flexurally rigid in the lateral direction.
However, the disadvantage of the known springs is, for example, that they are simultaneously flexurally resilient in the lateral direction (first alternative) or in the vertical direction (second alternative), so that these springs are not well suited for use as torsion springs, since the movable torsion mass undergoes deflection under lateral and vertical acceleration forces. This may result in undesirable interference signals or even striking against the structure.
In this regard, optical microscanners and optical CD read/write devices having T-profile springs are known from unexamined European Patent Application EP 1 234 799 A2 and from U.S. Pat. No. 6,552,991 B1, to which a micromirror is attached which may be tilted in different directions with the aid of suitable driving electrodes.